This fabulous article was prompted by the (hugely expected) to-and-fro of the tech commentariat about Apple's launch of their Watch.
It's an excellent object lesson in understanding the product landscape, and its fundamental lesson is: you are not - or certainly unlikely to be - the ideal customer for your own product or service. Even if you are the ideal customer (after all, plenty of people start a business to create things that they themselves like), you're certainly not the only demographic or customer.
This is important for communicators and copywriters too. We don't write and produce for CEOs, founders or boards. We produce for customers and slices of the market - slices which are becoming ever thinner. It's never been more important to know who you're talking to.